The FACS and FISH Core provides phenotypic cell cycle and genotypic analysis and separated cell populations to the investigators of this program project. The laboratory has developed cutting edge techniques in single cell analysis. For the quantitation of apoptotic cells, the TdT-b- dUTP assay (TUNEL) was modified for multi-parameter analysis in combination with DNA and BudR measurements (cell cycle, ploidy). Also, immunophenotypic analysis of dendritic cells (Project 4) and of progenitor cells, analysis of intracellular proteins related to apoptosis (bcl-2, bax) (Project 1), and of cell surface antigens including fas and MDR1 is provided. Expression of new regulators of apoptosis (Project 2) will be analyzed in normal and leukemic cells. Binding of Annexin V to phosphatidyl serine (PS) is utilized for testing changes in the membrane lipid structure associated with apoptosis. New assays to measure changes in the mitochondrial membrane potential and of cytochrome c in cells initiating apoptosis (CMXRos) and the detection of cleaved caspase 3 (Caspa-Tag Ph-phi Lux) are conducted for Projects 1, 4 and Core A. Quantitation of cellular antigens allows us to determine the Antibody Binding Capacity (ABC). Cd34 cells are MACS separated for subsequent analysis by FACS. Cell kinetic changes are determined in vitro by DNA/Ki67/CD34/CD38 FCM and the number of actual cell divisions is determined by pkh26 labeling., with cells undergoing one or up to ten divisions being separated by FACS for subsequent molecular analysis (Project 1). Cell cycle kinetics is determined in patients by infusions of IudR and BudR (Projects 1 and 3, Core A). Fluorescence in situ hybridization (FISH) determines the number of clonal leukemic interphase or metaphase cells. The combination of FISH and TUNEL of PS/Annexin V assay allows to discriminate apoptosis in normal and leukemic cells (Projects 1 and 4). Finally, progenitor and stem cell compartments (CD34+38-, CD34+KDR+ and CD34-lin- cells that eliminate Hoechst 33342, so-called "SP" cells) are sorted for investigations of XIAP and survivin in Project 1 and are analyzed for the presence of clonal leukemic and normal cells. The core provides critical support for all Projects and for Core A (clinical trials).